The human body includes various lumens, such as blood vessels or other passageways. A lumen may sometimes become at least partially blocked or weakened. For example, a lumen may be at least partially blocked by a tumor, by plaque, or both. An at least partially blocked lumen may be reopened or reinforced with an implantable stent.
A stent is typically a tubular body that is placed in a lumen of the body. A stent may be delivered inside the body by a catheter that supports the stent in a reduced-size configuration as the stent is delivered to a desired deployment site within the body. At the deployment site, the stent may be expanded so that, for example, the stent contacts the walls of the lumen to expand the lumen.
A guide wire may be employed when delivering a delivery catheter and stent to a desired location. For example, a guide wire may be advanced through a guiding catheter until the distal tip of the guide wire extends just beyond the location where the stent is to be implanted. A catheter and a stent to be positioned may be mounted onto the proximal portion of the guide wire, and the catheter and stent may be advanced over the guide wire until the catheter and stent are disposed within the blood vessel or other passageway where the stent is to be implanted. Once the stent is implanted, the catheter may be withdrawn over the guide wire. The guide wire may also be withdrawn, and the stent typically left in place.
Guide wires may often include an elongate core member with one or more segments near the distal end that taper distally to smaller cross-sections. One major requirement for guide wires is that they provide sufficient column strength to be pushed through the patient's vasculature or other body lumen without buckling. On the other hand, they must be sufficiently flexible to avoid damaging the body lumen as they are advanced. Efforts have been made to improve both strength and flexibility of guide wires to make them more suitable for these purposes, although these two desired characteristics are generally diametrically opposed to one another, such that an improvement in one typically results in less satisfactory performance relative to the other. For example, it is desirable that the distal portion of the guide wire be relatively more flexible in order to be more easily navigable through the patient's vasculature, which may be quite tortuous in portions. The proximal portion may be increasingly stiff, to provide the ability to support a balloon catheter or similar device.
Despite a number of different approaches for addressing these issues, there still remains a need for improved guide wires and associated methods of manufacture.